How to Replace a Cast Iron Main Sewer Line With PVC

Excavate the old sewer line if applicable. Many iron sewer lines run under the concrete slab, so cut through the slab with a jack hammer to expose the line. Use a shovel to dig into the dirt under the slab to uncover the line.

Attach the chain of a snap cutter around the sewer main, and press the handles of the cutter together to snap the pipe. Cut the sewer main into three or four 1-foot long sections for easier removal. Lift the pipes out, and discard them by taking them to a salvage yard.

Make the connections to the incoming sewer main line by installing an iron-to-PVC sleeve over the incoming connection. An iron-to-PVC sleeve is a pipe sleeve made of rubber that fits over the iron and PVC pipes. The sleeve also has a metal collar that tightens to clamp the sleeve in place. Slide the sleeve over the pipe until half of the sleeve covers the pipe. With a screwdriver, turn the collar to tighten the connection.

Install the first section of PVC pipe by inserting it into the sleeve and tightening the connection with the screwdriver. Apply PVC cement to the pipes and all the fittings, and then install the remaining sections by routing the pipe along the same path as the old sewer line. Make all the old connections with the proper fittings as necessary for your sewer line.

Cover the new pipe with the dirt you excavated, and fill the area around the pipe with gravel. Apply mortar over the pipe with a trowel to fill in the space and to repair the excavated concrete slab. Let the mortar dry for 24 hours before walking on top of the repaired area.